Abstract
The magnetic properties of a low-Curie-temperature Mg1+1Fe2-2xTixO4 system, which could be used in magnetic induction hyperthermia, were investigated. The thermo-magnetization curves and magnetic susceptibilities at high temperatures for water-quenched and slow-cooled Mg1+1Fe2-2xTixO4 samples were measured. The Curie temperature decreased with increasing Ti concentration x and increasing cooling rate. Rietvelt analysis was performed to determine the site occupancy at A and B sites of the constituent atoms in the spinel structure. The exchange interactions, JAB, JAA ,and JBB, were then estimated by molecular field theory. The calculated Curie temperatures as a function of x and those for samples with different heat treatments were in good agreement with experimental data. The effect of the inter-atomic angle φ between Fe-O-Fe on the Curie temperature was also investigaed under the super-exchange interaction regime. The reduction of the super-exchange interaction owing to the increase in angle φ contributes to decrease the Curie temperature.
